Reference is made to prior-art U.S. Pat. No. 3,371,521 for Leak-Testing Apparatus for Either Flush or Shouldered Pipe Joints and Packer Therefor. Reference is also made to U.S. Pat. Nos. 3,975,945 and 4,099,405, the former being entitled Apparatus for Testing Pipes for Leaks and the latter being entitled Apparatus and Method for Testing Pipe for Leaks, and Seals Therefor.
U.S. Pat. No. 3,371,521 relies on hooks 17 to maintain the casing closed despite the high fluid pressures contained therein. Such U.S. Pat. No. 3,371,521 also relies on a large packer 21 for sealing purposes.
U.S. Pat. No. 3,975,945 shows an apparatus adapted to contain higher pressures than that of U.S. Pat. No. 3,371,521, but which uses a vertically movable lock pin 20 to lock the casing in closed condition.
U.S. Pat. No. 4,099,405 claims seals which are not a continuous large packer, but instead in the nature of individual strips (reference being made, for example, to FIG. 7).
The present apparatus also employs hooks, not a vertically movable pin, for locking purposes, but has a surprising construction whereby more hooks may be employed for an apparatus of a given size to thus drastically increase the strength of the apparatus without requiring a vertically movable lock pin. The present apparatus also incorporates a packer, but one which will contain much greater fluid pressures than will the packer of U.S. Pat. No. 3,371,521.